JavaGroups is provided in .tar.gz and .zip form. In the first case, use gzip and tar to unzip and untar it, in the second case, unzip will do. A directory JavaGroups with several subdirectories will be created. Add this directory to your CLASSPATH, e.g.:
export CLASSPATH=$CLASSPATH:/home/mydir
(JavaGroups would be in /home/mydir/JavaGroups). Note that it is probably advisable to add a period (.) to your CLASSPATH so that class files in the current directory are found correctly (e.g. for the demo programs).
All the class files are already available in the source distribution, so you only need to recompile if you have modified some files. To recompile, type make all in the JavaGroups directory. If you also want to create the iBus adapter (class IbusChannel), type make ibus. (You need to have the iBus classes if you want to do this). To create the demo applications, type make demos.
Note that the above description applies to a UNIX like environment, where tools like make are available. In a different environment, e.g. a project builder, source files may have to be added to a project list, depending on the builder.